The present disclosure relates to detergent compositions that contain both cationic bleaching agents and polymers incorporating cationic groups.
Cationic polymers are known to deliver glass corrosion protection and color protection benefits in automatic dishwashing formulations. It is believed that the polymer forms a coating on the glass surface, protecting the surface from attack by other ingredients within the formulation. Examples of cationic polymers that reduce corrosion of dishware in an automatic dishwashing machine, include those described in U.S. Pat. No. 5,981,456 (Unilever), the contents of which are incorporated herein by reference. Amphoteric polymers (containing both cationic and anionic groups within the same structure) are known to provide anti-spotting benefits. It is believed that amphoterics suspend proteinaceous soil fragments that are thought to be responsible for spots. In addition, the cationic portion of the amphoteric polymer structure can cause the polymer to be adsorbed onto glass surfaces, thereby providing a sheeting action to the water and contributing to spotless glasses. Examples of amphoteric polymers include water-soluble aminoacryloyl-containing polymers, such those described in U.S. Pat. No. 5,308,532 and EP 0 560 519 B1 (both of Rohm and Haas Company).
Bleaching compositions and bleach systems are also well known and provide desired cleaning properties in many commercial detergents. Chlorine and N,N,Nxe2x80x2,Nxe2x80x2-tetraacetylethylenediamine (TAED)/perborate, for example, are well known for their bleaching properties. Cationic bleach systems that include cationic nitrites in the presence of peroxide are also known (see, for example, U.S. Pat. Nos. 5,236,616 and 5,281,361, EP 0 303 520 B1 and WO 99/63038, the contents of which are incorporated herein by reference). Other known cationic group containing organic bleach activators or bleach catalysts include, for example, cholyl(4-sulfophenyl)carbonate (CSPC, see, for example, U.S. Pat. No. 5,106,528 and EP 399,584 B1), quaternary imine salts (e.g. N-methyl-3,4-dihydroisoquinolinium p-toluenesulfonate, U.S. Pat. Nos. 5,360,568, 5,360,569 and 5,370,826). Several different types of cationic peracid bleach activators have been disclosed in EP 0 699 745, U.S. Pat. Nos. 5,599,781, 5,520,835, the contents of which are incorporated herein by reference. Cationic peroxyacids, such as those described in U.S. Pat. Nos. 5,908,820, 5,422,028, 5,294,362 and 5,292,447, have also shown good bleaching activity over a wide range of pH conditions.
Transition metal-containing bleach catalysts such as [MnIV2(xcexc-O)3(Me3TACN)2](PF6)2 (U.S. Pat. Nos. 4,728,455, 5,114,606, 5,153,161, 5,194,416, 5,227,084, 5,244,594, 5,246,612, 5,246,621, 5,256,779, 5,274,147, 5,280,117), [FeII(MeN4py)(MeCN)](CIO4)2 (EP 0 909 809) and [CoIII(NH3)5(OAc)](OAc)2 (U.S. Pat. No. 5,559,261, WO 96/23859, WO 96/23860, WO 96/23861), also exhibit cationic character under typical wash conditions.
In machine dishwashing applications, removal of bleachable stains, e.g. tea stains, is a particularly desirable property. Incomplete removal of such stains is readily noticeable and can lead to consumer dissatisfaction with the responsible detergent.
During the course of investigating various machine dishwashing compositions, it was unexpectedly discovered that the addition of polymers containing cationic monomeric units to formulations having known bleaching systems negatively affected tea stain removal. For example, when water-soluble amphoteric polymers, such as quaternized aminoacryloyl-containing polymers, were added to formulations containing TAED/perborate, the ability of the formulation to remove tea stains was significantly reduced.
Therefore, it was discovered that there is a need for machine dishwashing formulations that have both bleach and sheeting/anti-spotting ingredients or ingredients that provide color protection and/or corrosion prevention (i.e. care enhancing) properties, wherein the formulation does not negatively impact the ability of the bleach to reduce tea stains.
It has been found that machine dishwashing detergent formulations containing polymers having cationic monomeric units in combination with a bleaching agent can provide the desired bleaching benefit if the beaching agent also has a cationic group. A preferred formulation has a bleach system having at least one cationic group and a polymer having at least one monomer unit having a cationic charge over a portion of the pH range 2-11. Detergent formulations that do not combine a cationic polymer portion with a cationic bleach exhibit the discovered undesirable bleaching properties.
The present disclosure primarily relates to detergent formulations that are suitable for use in machine dishwashers. The formulations disclosed herein can be powder, tablet, block, gel, liquid, solid or semi-solid.
Suitable formulations generally include one or more of the following ingredients: both phosphate and nonphosphate (e.g. sodium citrate) builders; pH buffering agents; silicates; bleaches and bleaching systems including bleach catalysts; surfactants; enzymes; enzyme stabilization systems; thickeners; stabilizers and/or co-structures; fillers; defoamers; soil suspending agents; anti-redeposition agents; anti-corrosion agents; ingredients to enhance decor care; anti-tarnish agents; rinse aids; colorants; perfumes; and other known functional additives. More specific examples of the above and other known machine dish detergent ingredients are disclosed, for example, in U.S. Pat. Nos. 5,695,575, 5,705,465, 5,902,781, 5,904,161 and 6,020,294, the contents of which are incorporated herein by reference.
Suitable phosphate and non-phosphate formulations in accordance with the present disclosure include the following:
In all examples, the following base formulation was used:
For simplicity, Table C sets forth several abbreviations used in the text of the present disclosure.
Experimental Conditions
All dishwashing machine tests were carried out using a Miele G656 dishwasher setting at the 55xc2x0 Normal program, which accommodated main wash, pre-rinse and final rinse cycles. Water hardness was adjusted to contain 300 ppm of total hardness (Ca2+:Mg2+=4:1, expressed as CaCO3) and 320 ppm of temporary hardness expressed as sodium bicarbonate (i.e. 300/320 ppm water hardness). Soil load includes 20 g of ASTM standard food soil (a 4:1 wt/wt ratio of margarine/powdered milk) spread on the dishwasher door and 5 g of raw egg yolk dosed at the dispenser cup opening during the main wash cycle. In addition, 6 tea stained cups, 6 drinking glasses, 2 Tupperware containers, 1 melamine plate, 1 Teflon-coated frying pan and 16 clean plates were also present in the dishwasher to mimic the actual washing conditions.
In a typical machine test, 18 g of the base formulation (Table B, excluding bleach activator or glass appearance/care enhancing polymers) was used, unless noted otherwise. Bleach activator and/or glass appearance/care enhancing polymers were introduced separately at the dispenser cup opening during the main wash cycle.
At the end of each test, tea cups were scores based on area covered by and intensity of residual tea stain, expressed on a 0 to 5 scale, 0 being completely cleaned. Drinking glasses and plastic ware were also visually assessed and scored according to extent of spotting and filming. Both spotting and filming scores were recorded based on area covered by and intensity of spots/film, and also expressed on a 0 to 4 scale for spotting and a 0 to 5 scale for filming, 0 being completely free of spots or film.
Examples 1-3 detail the negative effect on tea stain removal caused by an amphoteric polymer (PC2 Polymer) in the presence of a neutral or anionically charged bleach activator, such as TAED, SNOBS and P-15.
Examples 4-6 illustrate the beneficial effect of peroxyacid bleach incorporating a cationic group into an automatic dishwashing detergent formulation that contains a glass appearance improving polymer.
Examples 7-9 demonstrate the synergistic effect of combining transition metal bleaching systems that are cationically charged, and PC2 Polymer, giving both tea stain removal and glassware despotting benefit.
Example 10 further teaches the effect of cationic polymer (e.g. Celquat H-100) against tea stain removal. Similar to previous examples, the deficiency in tea stain removal caused by the cationic polymer can be mitigated by the use of a cationic peroxyacid bleaching agent (e.g. cationic nitrile) or a transition metal-containing bleach catalyst.
Example 11 expands the use of a dishware care-enhancing cationic polymer (Merquat 3331). The combination of such polymer and a cationic bleaching system provides multifunctional benefits in machine dishwashing applications, including dishware fading and corrosion prevention, glass appearance-enhancing and cleaning efficacy on tea stains.